Is there a sub $100 PWM DC motor power supply suitable for treadmill motors,
with a rheostat control for manual speed setting plus a CNC control input, with
a switch connection to select between them?
I tried one of those wee little $20 Chinese ones with a 1+ HP, 110+ volt
treadmill motor. Almost worked, once I got wires to stay connected in the
CNC/manual speed control wire I made from a CD-ROM audio cable. When you apply
plenty of solder and shrink tube, one tends to expect the wire to *stay
connected*. I'm not at all a soldering newb.
The silly thing doesn't have a fail-OFF mode if there's not two pins jumpered
on the three pin header for selecting manual or PWM control input. It tries to
go full blast. Well, connected to this motor that turns the little 5 amp fuse
into a flashbulb, then it quits.
So yesterday I checked my switch wiring again and installed a fuse holder to
use 7 amp ceramic slow blow fuses, soldered the wires to the ends of a blown 5A
fuse. All hooked up and it ran great. I was able to run the speed up and down
with the knob just fine.
So I carefully tucked the wiring all into the box on the back of the 9x20
headstock, installed the screws then plugged in the power cord and flipped the
power switch. The spindle lurched a little and stopped. @#%@#%@#$^#$$^$@^!!!!!
Broken wire again! No F-in-way. Could NOT be, not after I'd taken that cable
all apart and made ##%^^ certain it could not fail again.
I was right, continuity good on all three wires. I checked all connections
again, PERFECT. Exactly as they were before I buttoned it up. Put in another
fuse and same thing, insta-pop of the fuse.
Soooo, it does look like the output rating of that little power supply is
somewhat overly optimistic, even after I made certain all the components
touching the heat sink were actually flat against it, with compound added, and
the screws holding it all together were tight. Must have blown some component
on it.
Oh well, it was cheap, and unlike the 1995 vintage controller from the
treadmill the motor came from it would run the motor smoothly from nothing up
to the point the 5A fuse decided it self-identified as an incandescent
lightbulb.
The treadmill controller would not send power to the motor until the knob was
turned up to 50%, then it would start it at that fast speed. It could be slowed
down after starting, but turning it down too quickly would make it cut power to
the motor. Completely unsuitable for a lathe. Got a few $ for it on eBay.
On the good side I do have the drive belt connecting the leadscrew stepper to
that ball screw. I went with the XL style since I already had a 22 tooth pulley
with 3/8" bore. I got a super deal on a 44 tooth XL pulley with 10mm bore on
jet.com Only had to drill and tap a couple of set screw holes. Yes, I am mixing
metric and SAE with wild abandon. Scrounging and intensive price shopping like
mad. The lathe only cost me $50 in practically new condition, and I've sold $75
in parts I've removed from it. :)
------------------------------------------------------------------------------
Mobile security can be enabling, not merely restricting. Employees who
bring their own devices (BYOD) to work are irked by the imposition of MDM
restrictions. Mobile Device Manager Plus allows you to control only the
apps on BYO-devices by containerizing them, leaving personal data untouched!
https://ad.doubleclick.net/ddm/clk/304595813;131938128;j
_______________________________________________
Emc-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/emc-users
